全文获取类型
收费全文 | 437篇 |
免费 | 27篇 |
国内免费 | 47篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 32篇 |
妇产科学 | 1篇 |
基础医学 | 34篇 |
口腔科学 | 13篇 |
临床医学 | 72篇 |
内科学 | 96篇 |
皮肤病学 | 14篇 |
神经病学 | 10篇 |
特种医学 | 148篇 |
外科学 | 9篇 |
综合类 | 11篇 |
预防医学 | 12篇 |
药学 | 43篇 |
肿瘤学 | 14篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 4篇 |
2015年 | 11篇 |
2014年 | 4篇 |
2013年 | 9篇 |
2012年 | 2篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 6篇 |
2008年 | 9篇 |
2007年 | 37篇 |
2006年 | 4篇 |
2005年 | 7篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 15篇 |
1998年 | 27篇 |
1997年 | 36篇 |
1996年 | 29篇 |
1995年 | 26篇 |
1994年 | 20篇 |
1993年 | 23篇 |
1992年 | 18篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 19篇 |
1988年 | 20篇 |
1987年 | 10篇 |
1986年 | 15篇 |
1985年 | 15篇 |
1984年 | 7篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 14篇 |
1976年 | 9篇 |
1975年 | 4篇 |
排序方式: 共有511条查询结果,搜索用时 15 毫秒
91.
SA Rabacchi JM Solowska B Kruk Y Luo JA Raper DH Baird 《The Journal of neuroscience》1999,19(11):4437-4448
Most axons in the CNS innervate specific subregions or layers of their target regions and form contacts with specific types of target neurons, but the molecular basis of this process is not well understood. To determine whether collapsin-1/semaphorin-III/D, a molecule known to repel specific axons, might guide afferent axons within their cerebellar targets, we characterized its expression by in situ hybridization and observed its effects on mossy and climbing fiber extension and growth cone size in vitro. In newborn mice sema-D is expressed by cerebellar Purkinje cells in parasagittal bands located medially and in some cells of the cerebellar nuclei. Later, sema-D expression in Purkinje cells broadens such that banded expression is no longer prominent, and expression is detected in progressively more lateral regions. By postnatal day 16, expression is observed throughout the cerebellar mediolateral axis. Collapsin-1 protein, the chick ortholog of sema-D, did not inhibit the extension of neurites from explants of inferior olivary nuclei, the source of climbing fibers that innervate Purkinje cells. In contrast, when it was applied to axons extending from basilar pontine explants, a source of mossy fiber afferents of granule cells, collapsin-1 caused most pontine growth cones to collapse, as evidenced by a reduction in growth cone size of up to 59%. Moreover, 63% of pontine growth cones arrested their extension or retracted. Its effects on mossy fiber extension and its distribution suggest that sema-D prevents mossy fibers from innervating inappropriate cerebellar target regions and cell types. 相似文献
92.
HPLC法测定地西泮和艾司唑仑的血药浓度 总被引:9,自引:0,他引:9
建立HPLC法同时测定地西泮和艾司唑仑血药浓度。方法:以Ultrasphere-ODS5μm4.6mm*25cm色谱柱为分离柱,流动相:甲醇-乙腈-水(40:20:40);检测波长为254nm,以外标法峰面积定量。结论本法可用于血药浓度测定。 相似文献
93.
Kirsten JE Asmus-Szepesi Paul L de Vreede Anna P Nieboer Jeroen DH van Wijngaarden Ton JEM Bakker Ewout W Steyerberg Johan P Mackenbach 《BMC geriatrics》2011,11(1):1-17
Background
Elderly persons admitted to the hospital are at risk for hospital related functional loss. This evaluation aims to compare the effects of different levels of (integrated) health intervention care programs on preventing hospital related functional loss among elderly patients by comparing a new intervention program to two usual care programs.Methods/Design
This study will include an effect, process and cost evaluation using a mixed methods design of quantitative and qualitative methods. Three hospitals in the Netherlands with different levels of integrated geriatric health care will be evaluated using a quasi-experimental study design. Data collection on outcomes will take place through a prospective cohort study, which will incorporate a nested randomised controlled trial to evaluate the effects of a stay at the centre for prevention and reactivation for patients with complex problems. The study population will consist of elderly persons (65 years or older) at risk for functional loss who are admitted to one of the three hospitals. Data is prospectively collected at time of hospital admission (T0), three months (T1), and twelve months (T2) after hospital admission. Patient and informal caregiver outcomes (e.g. health related quality of life, activities of daily living, burden of care, (re-) admission in hospital or nursing homes, mortality) as well as process measures (e.g. the cooperation and collaboration of multidisciplinary teams, patient and informal caregiver satisfaction with care) will be measured. A qualitative analysis will determine the fidelity of intervention implementation as well as provide further context and explanation for quantitative outcomes. Finally, costs will be determined from a societal viewpoint to allow for cost effectiveness calculations.Discussion
It is anticipated that higher levels of integrated hospital health care for at risk elderly will result in prevention of loss of functioning and loss of quality of life after hospital discharge as well as in lower burden of care and higher quality of life for informal caregivers. Ultimately, the results of this study may contribute to the implementation of a national integrated health care program to prevent hospital related functional loss among elderly patients.Trial registration
The Netherlands National Trial Register: NTR2317 相似文献94.
Summary
This study examined the effects of quercetin on spontaneously contracting portal veins isolated from healthy young adult male and female Wistar rats (250–300 g). Quercetin (10-7–10-4 M) always produced significant biphasic effects, comprising an initial brief stimulant effect (rise in basal tone), followed by a sustained, longer-lasting secondary relaxant (inhibitory) effect on the venous tissues. The initial brief contractions of the venous muscle preparations were not modified by preincubation of the tissues with prazosin (10-6 M), suggesting that the initial upsurge in basal tone and increases in contractile frequencies of the venous tissues were probably not mediated via alpha1-adrenoceptor stimulation. However, preincubation of the tissues with nifedipine (10-7 M) significantly suppressed (p < 0.05) or attenuated the initial stimulant effect of quercetin, suggesting that the flavonoid might be activating L-type voltage-dependent calcium channels. The vasorelaxant effect of quercetin was partially but not significantly (p > 0.05) inhibited by L-NAME (100 μM) or indomethacin (10 μM), suggesting that the vasorelaxant effect of the flavonoid was unlikely to be mediated via endothelium-dependent relaxing factor (EDRF), or through prostacyclin (PGI2) pathways. N-p-tosyl-l-phenylalanine-chloromethyl-ketone (TPCK, 3 μM) significantly (p < 0.01) antagonised quercetin-induced relaxations, suggesting that cAMP-dependent protein kinases might have contributed, at least in part, towards the vasorelaxant effect of quercetin on rat isolated portal veins. 相似文献95.
96.
Simon T Hero B Hunneman DH Berthold F 《European journal of cancer (Oxford, England : 1990)》2003,39(13):1899-1903
The value of the tumour markers vanillylmandelic acid (VMA) and homovanillic acid (HVA) in urine (u) and serum (s), neurone-specific enolase (NSE), and lactate dehydrogenase (LDH) in the early prediction of relapse/progression in neuroblastoma is not known. We analysed the data of neuroblastoma patients who had successfully completed first-line treatment and had laboratory results available from their initial diagnosis and from relapse/progression (n=196). Patients' overall survival from relapse or progression was 21.5+/-4.2% (mean+/-standard deviation). At diagnosis, we found abnormal results in 75% for VMA and/or HVA (s), 92% for VMA and/or HVA (u), 90% for NSE, and 81% for LDH. We found a lower incidence of abnormal results at relapse or progression with 40% for VMA and/or HVA (s), 54% for HVA and/or VMA (u), 61% for NSE, and 48% for LDH. Sensitivity of all markers was higher for metastatic compared with local recurrence. NSE was the best, being able to detect 42% of the localised relapses, 77% of the combined local/metastatic relapses, and 69% of the metastatic recurrences. Relapse or progression in neuroblastoma cannot be detected reliably by monitoring tumour markers alone. Therefore, follow-up of neuroblastoma patients must include clinical assessment and imaging studies. 相似文献
97.
Luuk DH Munsterman Paul WG Elbers Alaattin Ozdemir Eric PA van Dongen Mat van Iterson Can Ince 《Critical care (London, England)》2010,14(4):1-7
Introduction
The Intra-Aortic Balloon Pump (IABP) is frequently used to mechanically support the heart. There is evidence that IABP improves microvascular flow during cardiogenic shock but its influence on the human microcirculation in patients deemed ready for discontinuing IABP support has not yet been studied. Therefore we used sidestream dark field imaging (SDF) to test our hypothesis that human microcirculation remains unaltered with or without IABP support in patients clinically ready for discontinuation of mechanical support.Methods
We studied 15 ICU patients on IABP therapy. Measurements were performed after the clinical decision was made to remove the balloon catheter. We recorded global hemodynamic parameters and performed venous oximetry during maximal IABP support (1:1) and 10 minutes after temporarily stopping the IABP therapy. At both time points, we also recorded video clips of the sublingual microcirculation. From these we determined indices of microvascular perfusion including perfused vessel density (PVD) and microvascular flow index (MFI).Results
Ceasing IABP support lowered mean arterial pressure (74 ± 8 to 71 ± 10 mmHg; P = 0.048) and increased diastolic pressure (43 ± 10 to 53 ± 9 mmHg; P = 0.0002). However, at the level of the microcirculation we found an increase of PVD of small vessels <20 μm (5.47 ± 1.76 to 6.63 ± 1.90; P = 0.0039). PVD for vessels >20 μm and MFI for both small and large vessels were unaltered. During the procedure global oxygenation parameters (ScvO2/SvO2) remained unchanged.Conclusions
In patients deemed ready for discontinuing IABP support according to current practice, SDF imaging showed an increase of microcirculatory flow of small vessels after ceasing IABP therapy. This observation may indicate that IABP impairs microvascular perfusion in recovered patients, although this warrants confirmation. 相似文献98.
凝血酶肽促进缺血创面愈合与皮瓣存活的实验研究 总被引:1,自引:1,他引:0
目的探讨凝血酶受体激活肽(TP508)对促进缺血创面愈合与皮瓣存活的作用.方法SD大鼠66只,制作部分缺血创面(16只)、完全缺血创面(16只)、正常创面(18只)及皮瓣(16只)模型,每一模型又分为TP508治疗组和等渗盐水对照组.术后第3、7、10、14天,将创面或皮瓣坏死轮廓描记至醋酸纸七,输入计算机求出创面面积或坏死面积.结果术后7
d和14 d,TP508组正常创面面积仅为对照组的73.7%和45.4%.术后7 d,TP508组部分缺血创面面积为(99.8±30.7)mm2,而对照组为(128.0±43.4)mm2.术后第10天,TP508组完全缺血创面面积为(293.0±34.0)mm2,对照组为(352.4±41.2)mm2.术后第7天,TP508组皮瓣坏死面积为对照组皮瓣坏死面积的80.4%,第14天为56.8%.结论
TP508对促进大鼠缺血创面愈合和皮瓣存活均有显著作用. 相似文献
99.
Roth CL Hunneman DH Gebhardt U Stoffel-Wagner B Reinehr T Müller HL 《Pediatric research》2007,61(4):496-501
Severe obesity is a major problem in patients suffering from craniopharyngioma (CP), a benign tumor located in pituitary and hypothalamic regions. In this study, the hypothesis that hypothalamic damage leads to a reduction in overall sympathetic tone was tested. Catecholamines, as well as their metabolites homovanillic acid (HVA) and vanillylmandelic acid (VMA), markers of catecholamine turnover, were measured in morning voided urine of 109 patients participating in a German pediatric CP study, and their physical activity was analyzed using a questionnaire. HVA and VMA results were compared with age-matched HVA and VMA in urine of patients proven to not have a catecholamine-secreting tumor. Patients with the most severe obesity displayed the lowest urine HVA and VMA values. Patients with hypothalamic CP had 3.2-fold higher BMI values (p<0.0001), lower HVA (0.72-fold, p<0.001), and VMA (0.84-fold, p<0.01) values, and significantly lower activity scores than those without hypothalamic involvement, but their epinephrine- and norepinephrine/creatinine ratios were not significantly different, possibly due to low levels. The low HVA and VMA values suggest decreased sympathetic outflow contributing to reduced physical activity and severe obesity, especially in patients with a hypothalamic tumor. In further studies investigating treatment options for hypothalamic obesity, disturbed sympathetic tone should be considered. 相似文献
100.